The present invention relates to a head carriage device, and particularly relates to a head carriage device for use in loading a disc type recording medium (hereinafter, a disc type recording medium will be called a recording-medium disc) so that data can be written therein and read therefrom.
A first example of head carriage devices in related art will now be described with reference to FIG. 1. The head carriage device has a carriage 2, a lower magnetic head 5 fixed on an end of the carriage 2, a head arm 4, and an upper magnetic head 6 fixed on an end of the head arm 4. The head carriage device further has a leaf spring 7 and a torsion spring 9. In the first example, as shown in FIG. 1, the torsion spring 9 is supported by a supporting portion 2a which is protruded from the top of a pillar portion 8 provided at the other end of the carriage 2. The torsion spring 9 is located at a position higher than that of the head arm 4. The torsion spring 9 applies a downward force to the head arm 4, the direction of the applied force being such that the head arm 4 rotates in counter-clockwise direction.
However, in the head carriage device of FIG. 1, the torsion spring 9 for applying the downward (in FIG. 1) force to the head arm 4 is located on the top of the pillar portion 8. (The downward (in FIGS. 1, 2 and 3) force applied to the head arm 4 ensures that the magnetic heads 5 and 6 can access a magnetic disc to be inserted between the magnetic heads 5 and 6.) Thus, a magnetic disc apparatus which has the head carriage device of FIG. 1 therein needs a space to contain therein the torsion spring 9 on the top of the head carriage device of FIG. 1, the space having a height L.sub.1. The space may interfere with a miniaturization of the magnetic disc apparatus.
A second example of head carriage devices in related art will now be described with reference to FIG. 2. In the head carriage device of FIG. 2, a torsion spring 10 is supported by a supporting portion 2b which is protruded from the top of the pillar portion 8. A downward force is applied to the head arm 4 by means of the torsion spring 10, the direction of the applied force being such that the head arm 4 rotates in a counter-clockwise direction (in FIG. 2) so that the right end (in FIG. 2) of the head arm 4 downward (in FIG. 2) presses the upper magnetic head 6.
However, in the head carriage device of FIG. 2, the torsion spring 10 for applying the downward (in FIG. 2) force to the head arm 4 is located on the right side (in FIG. 2) of the pillar portion 8. Thus, a magnetic disc apparatus which has the head carriage device of FIG. 2 therein needs a space to contain therein the torsion spring 10 on the right side of the head carriage device of FIG. 2, the space having a length L.sub.2 thereof. The space may interfere with a miniaturization of the magnetic disc apparatus.
A third example of head carriage devices in the related art will now be described with reference to FIG. 3. In the head carriage device of FIG. 3, a tension spring (coil spring) 3 forces downward (in FIG. 3) a portion of the head arm 4, the portion of the head arm 4 being located near the leaf spring 7 supporting the head arm 4 therethrough. A downward force is applied to the head arm 4 by means of the tension spring 3, the direction of the applied force being such that the head arm 4 rotates in a counter-clockwise direction (in FIG. 3) so that the left end (in FIG. 3) of the head arm 4 downward (in FIG. 3) presses the upper magnetic head 6.
However, in the head carriage device of FIG. 3, the tension spring (coil spring) 3 for applying downward (in FIG. 3) force to the head arm 4 is located on the left side (in FIG. 3) of the pillar portion 8. Thus, a magnetic disc apparatus which has the head carriage device of FIG. 3 therein needs a space to contain therein the tension spring 3 on the left side of the pillar portion 8, the space having a length L.sub.3 thereof. A containing disc case which contains a magnetic disc to be accessed by the magnetic heads 5 and 6 may be inserted between the head arm 4 and the carriage 2, and the magnetic heads 5 and 6 access the magnetic disc contained therein. To insert such a case between the head arm 4 and the carriage 2, a space corresponding to the construction of the disc containing case is needed between the head arm 4 and the carriage 2, the space having a size large enough to prevent the spring 3 from interfering the insertion of the disc containing case. As a result of the provision of such a space for the case, the pillar 8 has to be located further to the right side (in FIG. 3) to provide in turn a sufficient space (having the length L.sub.3) for containing the spring 3, thus preventing the spring from interfering with the insertion of the case. However, such a locating of the pillar 8 further to the right (in FIG. 3) increases the overall size of the head carriage device, which may interfere with a miniaturization of the magnetic disc apparatus.
In summary, the above described problems of the head carriage devices in the related art prevent the magnetic disc apparatus to which one of the head carriage devices is applied from being miniaturized, such miniaturization including reduction of the thickness of the apparatus.